Naming Organic Compounds L. Scheffler Lincoln High School IB Chemistry 3-4. 1

Naming Organic Compounds Originally compounds were named based on their source or use Many organic compounds were given common names which are still in use However many ambiguities resulted With the large number of organic compounds, a method for systematically naming them is very important 2

IUPAC Names The International Union of Pure and Applied Chemists (IUPAC) developed a system for naming organic compounds. This system eliminated many of the ambiguities that plagued earlier naming systems Common names for many substances are still widely used 3

Naming Hydrocarbons using the IUPAC System A series of prefixes are used to designate the number of carbon atoms in a carbon chain meth 1 C hex 6 C eth 2 C hept 7 C prop 3 C oct 8 C but 4 C non 9 C pent 5 C dec 10 C 4

Naming Alkanes For straight chain hydrocarbons. The prefix indicates the number of carbon atoms. The suffix ane is added to designate that the compound is an alkane 5

Naming Alkanes with branched chains For branched chain hydrocarbons, identify the longest consecutive (straight) chain first. Then name the side chains or branches. The name of the branches end in “yl” and go before the name of the straight chain -methylpropane methyl butane dimethyl propane 6

Alkenes Alkenes have one (or more) carbon to carbon double bonds When there are 4 or more carbon atoms in a chain, the location of the double bond is indicated by a number. Numbering the location of the double bond(s) takes precedence over the location of side chains 1 butene 2-butene methylpropene 7

Naming Compounds With Functional Groups Various functional groups have unique suffixes that designate the functional group. The functional group takes precedence in numbering the carbon chain. Branches to the carbon chain are named in the usual manner. alcohols “ol” Amides “amide” Aldehydes “al” Amines “amine” or amino as a prefix Ketones “one” Ethers Ethoxy as prefix Acids “oic” halohydrocarbons Fluoro, bromo, chloro or iodo Esters “oate” 8

Alcohols Suffix = “ol” 1- Propanol 2- Propanol 2-methyl-2-propanol 9

Aldehydes and Alkanals Suffix = “al” Propanal Note that the aldeyhde group is always on an end carbon or carbon 1 10

Ketones or Alkanones Suffix = “one” Propanone (also known as acetone) Butanone (also known as methyl ethyl ketone) 2-Pentanone (note the number is necessary Because the C=O could be on carbon 2 or carbon 3) 11

Carboxylic Acids Suffix = “oic” Butanoic acid Note that the acid group (called a “carboxyl”) is always on an end carbon or carbon 1 12

Esters Esters Suffix = “oate” Ethyl butanoate Butyl ethanoate There are two branches. The branch with the carbonyl gets the suffix 13

Amides Suffix = “amide” butanamide Note that the amide group is always on an end carbon or carbon 1 14

Amines Suffix = “amine” Or prefix = “amino” Propylamine or 1-aminopropane 2-propylamine or 2-aminopropane 2-methyl-2-propylamine or 2-methyl -2- aminopropane 15

Halohydrocarbons 1-bromopropane 2 chlorobutane 1,2 diiodoethane Cis 1,2difluroethene Trans 1,2 difluoroethene 1,1,2 trifluorothene prefixes = “fluoro, chloro, bromo, iodo” 16

Ethers Suffix = “oxy”on first branch Ethoxyethane (diethylether) Ethoxybutane (ethylbutyl ether) 17

Aromatic Compounds With Functional Groups Benzoic acid 2 hydroxybenzoic acid 3 bromobenzoic acid 18

Nitriles Nitriles have a cyanide group. The name is based on the longest carbon chain that includes the carbon atom in the nitrile group. 19

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